Concentration effect of Sm3+ ions in B2O3-PbO-PbF2-Bi2O3-ZnO glasses - Structural and luminescence investigations

Concentration dependent spectroscopic properties of Sm3+ ions are investigated in the prepared xSm:PbFB lead fluorobororate glasses with the composition (40 x x)B2O3 + 20PbO + 16PbF(2) + 12Bi(2)O(3) + 12ZnO + xSm(2)O(3) (where x = 0.05, 0.1, 0.5, 1, 2and 3 wt.%). Surface morphological analysis and structural behaviors of the prepared glasses have been explored through SEM, EDX, XRD, FTIR and Raman spectral analysis. The amorphous nature of the prepared glasses have been confirmed through XRD spectral analysis. The presence of BO3, BO4, B-O-B and Pb/Bi-O-B vibrational stretching units in the prepared glasses are confirmed through FTIR and Raman spectral analysis. The optical characterizations were carried out using UV-vis-NIR absorption, luminescence spectra and decay curves of the present glasses. The calculated bonding parameter ((beta) over bar and delta) values reveal the ionic nature of the Sm-O bond in the prepared glasses. The Judd-Ofelt intensity parameters, Omega(lambda), were evaluated from the measure d oscilla tor strength of the various absorption bands to study the bonding environment around the Sm3+ ions in the prepared glasses. From the JO intensity parameters and emission spectral measurements, the radiative properties such as stimulated emission cross-section (sigma(E)(p)), branching ratio (beta(R)) and radiative lifetime (lambda(R)) for the H-6(J=5,7,9,11) emission transitions have been calculated. The experimental lifetime for the excited (4)G(5/2) level of the Sm3+ ions in the prepared glasses were calculated from the decay analysis and it is found to decrease with the increase in Sm3+ ion content. The decay curves are found to be non-exponential for the higher concentration of Sm3+ ion which is due to the efficient energy transfer between Sm3+-Sm3+ ions. To understand the nature of the energy transfer, the non-exponential decay rates were fitted to Inokuti-Hirayama (IH) model for S = 6 which reveals that the energy transfer process is of dipole-dipole in nature. Among the prepared glasses, 0.5 Sm PbFB glass exhibit higher values of emission characteristic parameters and quantum efficiency for the (4)G(5/2) level suggesting that 0.5SmPbFB glass could be useful for optoelectronic device fabrication and laser applications. (C) 2013 Elsevier B.V. All rights reserved.